Aircraft propeller construction



March 10, 1942.

G. ARMITAGE. SR., ET AL AIRCRAFT PROPELLER. CONSTRUCTION Filed April 29,- 1940 2 Sheets-Sheet l NVENTORS March 10, 1942- G. ARMITAGE, SR., ET IA1. l 2,275,599 y AIRCRAFT PROPELLER CONSTRUCTION Filed- April 29, 1940A 2 Sheets-Sheetl 2 Patented Mar. 10, 1942 OFFICE Maenner PROPELLER. ooNsTnUorroN Glen Armitage, Sr., and Glen Armitage, Jr., Redwood Falls, .Minn

Application April Z9, 1940, Serial No. 332,374

2 Claims.

This invention relates to improvements in air screws and especially is concerned with a novel air screw of the type comprising a pair of oppositely rotating propellers coacting to prevent slippage.

An important consideration in airplane design is that the vortex of the air screw pulling the airplane acts upon the airplane wings to impart an `upward lift to one` side and a downward thrust to the other commonly called propeller torque. A common expedient in the past for alleviating `this undesirable condition has been to provide weights or other `counteracting force in the wing against Whichthe lifting force operates. But this practice has resulted in disadvantageous conditions inasmuchas the propeller torque is dependent both upon the rate of rotation of the propeller and the velocity of the airplane to mention but two of several factors concerned. This undesirable situation, however, is corrected in the type of airplane construction to which `the, present invention relates by conjoint use of oppositely rotating air screws which impart opposite and hence neutralizing torques.

It is among the more important objects of this invention to provide a novel aircraft propeller construction wherein means is provided for simultaneously rotating in opposite directions a pair of propellers coacting with each other in a manner such that slippage is substantially pre' eluded.

Another object of this invention is to provide means for causing opposite rotation of two propellers operated from a common shaft without requiring the use of concentric shafts or the like.

An advantage of the propeller construction according to this invention and particularly the reversing drive thereof is that the unit or assem- `bly is symmetrical and balanced and may be mounted within the cowllng surrounding the propeller hubs.

Regarded in certain of its broader aspects the lili (Cl. mii-135.5)

novel propeller construction according to this invention comprises a pair of propellers, one rigidly and the other freely mounted upon a drive shaft; an internal gear connected to the freely mounted propeller, a spur gear mounted on the shaft and pinions coupling the internal and spur gears in a manner such that" the free propeller rotates simultaneously with but in a direction opposite to rotation of the drive shaft; and Cowling surrounding the hubs of the propellers and the gears above mentioned.

In order to facilitate a fuller and more com- .plete understanding of the present invention a specific embodiment thereof herein illustrated will be hereinafter described, it being clearly understood, however, that the illustrated embodiment, although presently preferred, is provided solely byway of'example of the practice of this invention and not by way of limitation thereof except insofar as the invention is recited in the subjoined claims.

Referring then to the drawings,

Figure l is substantially a Vertical sectional View of the presently preferred embodiment of this invention illustrating the same mounted on an engine as if in use,

Figs. 2 and 3 are respectively vertical transverse sectional views of Fig. 1 taken along the planes designated by the lines 2-2 and 3--3 thereof,

Fig. 4 is a side elevational View of the free propeller hub, and

Fig. 5 is a top plan view of the spider support forming a part of the device according to this in-` vention.

Referring now to the drawings it will be noticed that the novel propeller construction according to the present invention generally desig' nated by the reference character lil comprises a forwardly directed tubular extension block I I mounted by means of bolts i2 on an engine crank case front A, the block being positioned concentric the engine drive shaft B and being provided with a frustoconical bearing race Ha on the eX- ternal surface thereof substantially as shown. A spider I3 rigidly fastened by bolts i4 to the face of the block ll presents a plurality of radiating arms on which are mounted stud shafts I5 held upon the spider by bolts IS. The stud shafts extend in substantial parallelism to the axis of the engine drive shaft B and carry freely rotatable thereon pinion gears generally designated by the reference character Il, each of which comprises a large pinion Ila and a small pinion IIb formed from a single block of substance integrally with eachother. To 'facilitate free rotation of the pinions 'under circumstances of use,`s1eeves IIc are provided on thesurface facing the stud shafts A spur gear i8 rigidly mounted upon the engine drive shaft Boby means 'including tongues and grooves generally designated by the reference character I9 and bolts 20 meshes with the smaller of each of the pinion gears I1 whereby rotation ,of the drive shaftresults in rotation in opposite v22 by bolts 25 holds packing 26 in a manner such thatY the interior 'of the sleeve is substantially sealed as hereinafter will be described.

` Aninternal gear 21 mounted within the sleeve ZI` by fastening means 'Z'iaxmeshes with' the larger of the pinionsl Il in a manner such r that rotation of the engine dri-ve, .shaft B results in rotation in an opposite direction of the sleeve 2|.

'Av firstpropeller assembly comprising blades 28 mounted in a split hub12$lv connected `by bolts 3D and provided'with clamps generallydesignated 'by the reference character 3| for rigidly holding the blade shanks within the hub is positioned concentric the engine drive shaft B in a l agregarse vof the first propeller.

It is to be understood that this invention is capable of extended application and is not conned to the precise illustrated forms or described construction and, therefore; such changes and modifications may be made therein as do not affect the spirit of the invention nor exceed the scope of the appended claims. o

Having thus described the present invention, what it is desired to secure by Letters Patent is:

1. Aircraft propeller construction comprising a forwardly directed tubular extension block mounted on the. engine lcrank -case front and surrounding the drive shaft, said block having a frustoconical bearing race formed on the eX- ternal surface thereof; a rigid spider mounted on the block concentric with the shaft; stud shafts on the spider inparallelism to the drive shaft;` freely rotatable pinion `gears onthe stud shafts; a spur gear mounted on the drive shaft near the spider meshing with 'the pinion gears; a sleeve vcircumjacent the extension block and thespider extending forwardly concentric the drive shaft;

. a plate mounted on the back end of the sleeve locality near but infront of a spider and pinion o gear assembly yabove described the blades eX- tending through close fitting openings formed in the sleeve 2i. Forward motion of the propeller assembly is restricted by a collar 3E acting through ball bearings 33, the collarbeing held in place upon the;shaft by a bearing element 34 fixed onthe threaded shaft end with lock nuts 35. 4 The plate 38 attached tothe front end of the 4sleeve 2l by bolts 3l is provided with an inwardly directed frustoconical roller race 36a upon which runI rollers 3,8 cooperating` with the bearing member 34 above mentioned vin 'a manner l. such that the sleeve I` is permitted free-rotation mitting enclosure of the interior of the sleeve 2| by retaining lubricantv therein in a manner familiar to those skilled in this art.

A second propeller generally designated b-y the reference character C is rigidly mountedin a having an inwardly directed frustoconical bearing race formed therein' and rollers between said race andthe race on the extension block; an internal jgear on the sleeve meshing with the pinion gears whereby rotation of the drive shaft results in rotation but in an opposite direction of the sleeve.; a first propeller freely rotatably mounted on the drive shaft having blades eX- tending through openings in the sleeve whereby sleeve and propeller rotate as a unit; a conical roller bearing mounted on the 'shaft and a plate on the front of said sleevefcooperating with said conical rollerA bearing for holding the sleeve against axial motion along the drive shaft, said conicall bearing further serving to urge the first propeller toward the spider and prevent movement of the propeller along the shaft;l means for sealing lubricant within the sleeve; and a second propeller mounted on thefront end of the drive shaft' and rotating therewith.

ing an engine drive shaft, a propeller rigidly ,mounted on the outer end of said shaft, an elongated hollow hub surrounding the shaft and havhub affixed to the front of the shaft B and rotates ing its outer end provided with a bearing connection with the shaft and its inner end having a bearing connection with a crank case, said bearing connections comprising two sets of tapered roller bearings of oppositely directed tapered surfaces, a non-rotating spider carried by the crank case within the hub, a spur wheel on the engine shaft beyond the spider, freely rotatable pinions on the spider `and meshing with the spur wheel, an internal gear on the inner face of the elongated'hub and meshing with the pinion gears, and 1 propeller blades passing through the elongated hub intermediate the outer and inner bearings and rigidly mounted in a hub loosely mounted on the drive shaft.

GLEN ARMlTAGRSR. GLEN ARMITAGE, JR. 

